1. A geometric sequence has a common ratio. You can find the ratio by dividing every number by its previous one. If it is consistent, then the series is geometric. a: 8/1=8, 27/8=3.375 b: (-3/2)/3=-1/2, (3/4)/(-3/2)=-1/2 c. 7/4=1.75, 10/7=1.429 d. 20/25=0.8, 14/20=0.7
Choice b is the only one that has a common ratio, so it is a geometric series.
2. Every term is multiplied by 1/3, so the common ratio is 1/3. d is the answer.
